A recirculating powder applicator includes an applicator body having an inlet on an upstream surface and an outlet on a downstream surface, wherein the inlet and outlet define a passage that extends transversely through the thickness of the applicator body, a powder conduit, an air inlet, an exhaust aperture located on one of the upstream or downstream surfaces, and a circulation chamber located on the interior of the applicator body. The powder conduit and air inlet are in fluid communication with the passage and the passage is in fluid communication with the circulation chamber. A method of applying powder to a substrate during a continuous process includes using a recirculating powder applicator.
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1. A method of applying powder to a substrate during a continuous process, the method comprising the steps of:
providing a continuous run of a substrate through a powder applicator;
providing a metered flow of powder onto the substrate through a powder conduit of the powder applicator, wherein a first portion of the powder is deposited on the substrate from the powder conduit;
providing between 15 and 100 psi of air through an air inlet of the powder applicator simultaneously with the providing the metered flow of the powder, wherein the air recirculates a second portion of the powder within a circulation chamber of the powder applicator and wherein the second portion of powder is deposited on the substrate after being recirculated; and
exhausting the air through an exhaust aperture located within the circulation chamber of the powder applicator, wherein the exhausted air contains less than 5% of the powder dispersed within the air.
8. A method of applying a moisture barrier between a cable core and an armor, the method comprising the steps of:
receiving a run of cable core from a cable core payoff;
receiving a run of armor from an armor payoff;
forming the armor at least partially around the cable core during a first armor forming step;
applying a superabsorbent powder to the cable core and an interior surface of the partially formed armor, wherein the powder is applied using a powder applicator that comprises:
an applicator body including an inlet on an upstream surface and an outlet on a downstream surface, wherein the inlet and outlet define a passage that extends transversely through the thickness of the applicator body;
a powder conduit;
an air inlet;
an exhaust aperture located on one of the upstream or downstream surfaces; and
a circulation chamber located on the interior of the applicator body and including a depression formed around the exhaust aperture;
wherein the powder conduit and air inlet are in fluid communication with the passage and wherein the passage is in fluid communication with the circulation chamber; and
completing the forming of the armor around the cable core during a second armor forming step such that the armor surrounds the cable core.
2. The method of
4. The method of
10. The method of
11. The method of
providing a metered flow of powder onto the cable core and armor through a powder conduit of the powder applicator, wherein a first portion of the powder is deposited on the cable core and armor from the powder conduit;
providing between 15 and 100 psi of a gas through an air inlet of the powder applicator simultaneously with the providing a metered flow of powder step, wherein the gas recirculates a second portion of the powder within the circulation chamber of the powder applicator and wherein the second portion of powder is deposited on the cable core and armor after being recirculated; and
exhausting the gas through an exhaust aperture located within the circulation chamber of the powder applicator, wherein the exhausted gas contains less than 5% of the powder dispersed within the gas.
12. The method of
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This application is a divisional of U.S. patent application Ser. No. 15/338,572, filed Oct. 31, 2016, which claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Application No. 62/260,896, filed Nov. 30, 2015, and is incorporated herein by reference.
The disclosure relates generally to a powder applicator and more particularly to a powder applicator for a continuous process line. Various types of powder can be applied to products for a variety of reasons, such as to provide lubrication, to absorb moisture, and to color a surface. Often the object to which the powder is applied is produced on a continuous process line. Because powders are a collection of unconnected particles, powders can be difficult to control, especially when dispersed in the air. Additionally, powders tend to clump when exposed to moisture. Machinery for the application of powders often tends to be messy and inefficient (i.e., much of the powder is wasted during application) at applying powders to the substrate. Further, in a continuous process, clumps in the powder can disrupt the process line either by clogging the powder applicator or by creating a jam in downstream machinery.
One embodiment of the disclosure relates to a recirculating powder applicator, having an applicator body including an inlet on an upstream surface and an outlet on a downstream surface, wherein the inlet and outlet define a passage that extends transversely through the thickness of the applicator body; a powder conduit; an air inlet; an exhaust aperture located on one of the upstream or downstream surfaces; and a circulation chamber located on the interior of the applicator body. The powder conduit and air inlet are in fluid communication with the passage and the passage is in fluid communication with the circulation chamber.
An additional embodiment of the disclosure relates to a method of applying powder to a substrate during a continuous process, the method comprising the steps of providing a continuous run of a substrate through a powder applicator; providing a metered flow of powder onto the substrate through a powder conduit of the powder applicator, wherein a first portion of the powder is deposited on the substrate from the powder conduit; providing between 15 and 100 psi of air through an air inlet of the powder applicator simultaneously with the depositing step, wherein and the air recirculates a second portion of the powder within a circulation chamber of the powder applicator and wherein the second portion of powder is deposited on the substrate after being recirculated; and exhausting the air through an exhaust aperture located within the circulation chamber of the powder applicator, wherein the exhausted gas contains less than 5% of the powder dispersed within the air.
An additional embodiment of the disclosure relates to a method of applying a moisture barrier between a cable core and an armor, the method comprising the steps of receiving a run of cable core from a cable core payoff; receiving a run of armor from an armor payoff; forming the armor at least partially around the cable core during a first armor forming step; applying a superabsorbent powder to the cable core and an interior surface of the partially formed armor, wherein the powder is applied using a powder applicator that includes an applicator body including an inlet on an upstream surface and an outlet on a downstream surface, wherein the inlet and outlet define a passage that extends transversely through the thickness of the applicator body; a powder conduit; an air inlet; an exhaust aperture located on one of the upstream or downstream surfaces; and a circulation chamber located on the interior of the applicator body and including a depression formed around the exhaust aperture. The powder conduit and air inlet are in fluid communication with the passage and \the passage is in fluid communication with the circulation chamber. The forming of the armor around the cable core may then be completed during a second armor forming step such that the armor surrounds the cable core.
Additional features and advantages will be set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims.
The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and the operation of the various embodiments.
Referring generally to the figures, various embodiments of a recirculating powder applicator are shown. In one embodiment, the recirculating powder applicator is designed to apply a superabsorbent polymer (SAP) powder to the surface of an optical fiber cable core in order to provide a moisture barrier. For an optical cable, in particular, if moisture reaches the individual optical fiber strands, then the optical fiber can experience stress corrosion cracking caused by the reaction of water with silica at locations of strained bonding, such as at surface defects. Therefore, preventing moisture from reaching the optical fiber surface is an important factor in extending the life of an optical cable. While the following discussion will be framed in terms of the application of SAP powder to an optical fiber cable core, those skilled in the art will recognize from the following description that such embodiments are provided by way of example only, not by way of limitation, and that all alternative embodiments and applications are reserved herein.
A process diagram for forming a cable is depicted in
In a particular embodiment, while the armor is partially formed around the cable core, SAP powder is applied to the cable by a powder applicator 18. The SAP powder prevents the propagation of water along the cable should the armor be disrupted. After the application of SAP powder, the armor is formed completely around the cable core during a stage two armor forming step 20. A cable jacket is extruded around the armored cable core during a jacket extrusion step 22. The cable is cooled, such as by running the cable through a water trough, during a jacket cooling step 24. Finally, during a finished cable takeup step 26, the cable is spooled, or otherwise collected, for further processing or transport.
The cable forming process described above is a continuous process, i.e., a single run of cable passes continuously through each of these stages in the process. In some instances, more than one hundred kilometers of cable can constitute a single run of cable. Therefore, disruptions to the process, such as for splicing components or for unsticking kinks in the process line, can cause significant delays in cable production.
Armor 42 generally provides an additional layer of protection to the optical fibers 32 within cable 30, and may provide resistance against damage (e.g., damage caused by contact or compression during installation, damage from the elements, damage from rodents, etc.). As can be seen in
Because the SAP powder is applied between the cable core 41 and the armor 42, the SAP powder is applied between the two stages of armor forming in one embodiment. In a particular embodiment, the powder applicator 18 is a recirculating powder applicator as shown in
Beginning with
In a particular embodiment, the upstream plate 52 and downstream plate 54 are reversibly held together using a clamp 56. The clamp 56 generally includes a foot 58 that contacts the downstream plate 54. The foot 58 is attached to a first clamp arm 60. The upstream plate 52 is attached to a second clamp arm 62. The clamp 56 is actuated via a handle 64. In this way, the upstream plate 52 and downstream plate 54 can be reversibly joined such that access to the interior of the applicator body 50 is provided. In another embodiment, alignment means 65 are provided to facilitate assembly of the upstream plate 52 and downstream plate 54 of the applicator body 50. For example, the alignment means 65 can be a pin that mates with matching holes on the upstream plate 52 and downstream plate 54; a pin on one of the plates 52, 54 and a matching hold on the other of the plates 52, 54; or a peripheral ridge on one of the plates 52, 54 and a matching groove on the other of the plates 52, 54.
Provided on the exterior surface of the upstream plate 52 is an inlet 66, and provided on the exterior surface of the downstream plate 54 is an outlet 68. The inlet 66 and outlet 68 can be permanently or reversibly attached to the upstream plate 52 and downstream plate 54. In the exemplary embodiment depicted in
Turning to
The inlet 66 includes an opening 78, and the outlet 68 includes an opening 80 (shown in
In one embodiment, as shown in
The circulation region 96 of the circulation chamber 94 includes a depression 97. In one embodiment, the depression 97 is substantially centered on the exhaust aperture 74. As shown in
While passing through the applicator 18, the cable core 41 and armor 42 are coated with SAP powder. The SAP powder is provided via a powder supply line 102 connected to the powder conduit 84. The powder travels to the powder applicator 18 along the powder supply line 102 from a powder storage compartment. The storage compartment can be, for example, a volumetric feeder, a gravimetric feeder, dry cabinet, or a hopper. Controls for metering the powder can be provided with the storage compartment, on the powder supply line 102, or at the powder conduit 84. The metered flow of powder drops onto the cable core 41 and the interior surface of the armor 42. The impact of which causes mechanical separation of the powder particles.
Air flows into the powder applicator 18 via an air supply line 104 connected to the air inlet 86. The air is provided at a pressure between 15 and 100 psi to the air inlet 86 in order to create a high velocity, low volume jet that causes the mechanically separated particles to disperse and sends the particles on a circular flow path in the circulation chamber 94. The jet of air flows through the entrance region 95 and sweeps the bottom of the circulation region 96 clear of powder particles and creates cyclonic circulation within the circulation chamber 94. The powder is denser than the air, and thus, the cyclonic action causes the powder particles to travel along to the outer periphery of the circulation chamber 94. The break in the outer periphery in the region defining the transition between the entrance region 95 and the circulation region 96 causes the particles to leave the outer periphery at high velocity to be deposited on the moving cable core 41 and armor 42. Thus, under the influence of the air stream, the particles circulate around the circulation chamber until they return to the cable core 41 and armor 42. The jet of air within the circulation chamber also prevents the buildup of powder particles through the sweeping action mentioned above, which ensures that the total dwell time of powder within the powder applicator 18 is low. Accordingly, moisture in the air is not able to cause the SAP powder to clump.
Advantageously, the powder is applied only to the cable core 41 and inside surface of the armor 42. The powder sticks to the cable core 41 as a result of Van der Waals forces. In some embodiments, the inside surface of the armor 42 is oiled from corrugation step 14 or the stage one armor forming step 16, and the oil helps the SAP to stick to the armor 42. In the stage two armor forming step 20, the forming elements do not contact the inside surface of the armor 42, which might otherwise disrupt the uniform coating of the powder on the inside surface.
Using the above-described process, at least 95% of the powder that enters the powder applicator 18 is deposited on the cable core 41 and armor 42. Of the at least 95% of the deposited powder, a first portion of the powder is deposited directly onto the cable core 41 and armor 42 from the powder conduit 84. A second portion of the powder is circulated in the circulation chamber 94 before being deposited on the cable core 41 and armor 42. The remaining portion of the powder, which is, at most, approximately 5% of the powder, is exhausted through the exhaust aperture 74.
The powder is provided to the powder conduit 86 at a metered rate, such as, for example, approximately five grams per meter of cable core. This allows for precise control of the deposition rate over a wide range of production line speeds. Additionally, during application of the powder, equilibrium between the first portion of powder deposited directly onto the cable core 41 and armor 42, the second portion of powder circulated within the circulation chamber 94, and the powder contained in the exhaust gas will be achieved. Thus, a constant, metered, and controlled flow of powder can be maintained to provide a uniform distribution of powder onto the surface of the cable core 41 and armor 42 without concern of powder buildup within the powder applicator 18, which could cause clogging of the powder applicator or clumps to form between the cable core and the armor.
Application of the SAP directly to the cable in the form of a powder provides a material cost savings and a weight savings. Additionally, because a high percentage (between 95-97%) of the SAP is applied to the cable, there is no need to recycle the circulated powder. Recycling the powder can lead to clogging of machinery or deposition of clumps because the powder that has been exposed to the air will absorb moisture from the air. Because of the long processing times for cable runs of longer than one hundred kilometers, it is imperative to avoid an accumulation of SAP powder on the processing equipment because a single clump could create a bulge in the cable, which could upset the cable processing line.
Also advantageously, the powder applicator 18 can be made very compact. In one embodiment, the powder applicator is approximately 142 mm long and has only three required connections: one powder supply line 102, one air supply line 104, and one exhaust hose (not shown). This design allows the powder applicator to be placed in tandem between armor forming elements.
In another embodiment of the powder applicator 18 shown in
As can be seen in
The tapered interior surface 108 and the air nozzle 106 can be used in conjunction or separately. Additionally, the inlet 66 and outlet 68 can both feature the air nozzle 106 and the tapered surface 108, or the inlet 66 and outlet 68 can feature either the air nozzle 106 or the tapered surface 108. Moreover, the inlet 66 and outlet 68 do not have to match.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article “a” is intended to include one or more than one component or element, and is not intended to be construed as meaning only one.
It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.
Li, Ming, McAlpine, Warren Welborn, Blazer, Bradley Jerome, Conrad, Craig Miller
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